Carnosaurs are a subgroup of the theropoddinosaurs. They are the cladeCarnosauria. The term was once used very widely, but is now defined more narrowly. It is called by some authorities the Allosauroidea.[1]

Carnosaurs are characterized by several features. Some features must have been adaptations to their large size, such as their open skull, made of struts rather than solid bone. They had large eyes and a long, narrow skull. The femur ("thigh bone") is usually larger than the tibia ("shin bone"). This suggests close-to action was controlled by sight.

The legs are adapted for running, but not extremely so. They had strong arms, probably used to wrestle prey as the teeth bit in. The structure of an Allosaurus suggests a strongly-built general all-round predator. This is a different from a tyrannosaur like Albertosaurus, which was better adapted for running on open ground. Tyrannosaurs, with their small two-fingered hands, would use their heads for killing prey, and for head-butting rivals.